The present invention relates to electronic units formed by two printed-circuit type boards joined by assembling means and electrical conductors, and comprising a plug behind only one of these boards, the two boards being designed so that they are placed simultaneously between grooves of a support and so that, at the end of the insertion, the plug penetrates a corresponding plug receptacle that is fixedly joined to the support.
The insertion of a single board so that it is placed between grooves already requires a certain degree of care, and the difficulties of insertion are appreciably greater with an electronic unit formed by two boards especially when each of these two boards has a dissipative face designed to remove calories produced during the working of the board. Indeed, in this case, the dissipative faces of these two boards then have to be placed appropriately against the walls of the grooves in order to promote the dissipation of calories by conduction. In known units, the two boards enter between their respective grooves with hard friction and the operation proves to be difficult.